Over-wrapping a primary filament to fabricate a composite material

ABSTRACT

An improved filament winding method and apparatus for fabrication of composite material products is based on a mechanism that rotates filaments around a non-rotating mandrel. The primary filaments in predetermined patterns tend to move on the mandrel and thus such filaments are fixed in position relative to the mandrel by over-wrapping them with secondary filaments applied over the primary filaments. The winding mechanism functions by rotating filament spools around a non-rotating mandrel rather than rotating the mandrel to pull the filaments onto the mandrel. The mandrel is axially translated through the center of the winding mechanism or the winding mechanism is translated over a stationary mandrel which is supported in such a manner as to provide for such translation.

PREVIOUS FILING INFORMATION

[0001] On May 29, 2001 the United States Patent Office received a copyof—and assigned serial No. 60/294,195 to—a Provisional PatentApplication (PPA) filed by the same inventor hereof. That PPA isincorporated herein by this reference as though set out here in full.Additionally, the PPA is being supplemented by this Regular PatentApplication (RPA). Applicant expressly reserves all rights andprivileges flowing from the PPA and its earlier official filing date andcontents thereof. This RPA follows and is supported by the PPA.

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

[0002] This invention relates to filament winders used to applyfilaments to a support surface such as a mandrel. More specifically, thefield of this invention relates to the fabrication of filamentreinforced composite products. Additionally the field of this inventionrelates to winding of filaments and relative motion between filamentwinding machinery and a mandrel. The field of the winding method of theinvention envisions computer control of mandrels, spools and associatedfilament winding apparatus for the improved formation of diversecomposite material structures.

EXPLANATION OF TERMS

[0003] My invention interfaces and operates in conjunction with variousfilament winding and composite material forming technologies. Set outbelow are brief descriptions of certain relevant terms which further theunderstanding of the invention. These terms provide a basis for adetailed teaching of the improvements of this invention in the relevantarts. Such terms are not intended to replace the claims but rather serveas helpful guides in understanding my novel improvements in these arts.

Fiber Reinforced Composites

[0004] Fiber reinforced composites are materials consisting of amultitude of fibers which are surrounded and encased in a matrix. Thedesired properties of the composite may be structural, electrical,thermal or magnetic. These diverse properties are achieved by theappropriate selection of the matrix and fiber materials and by theorientation and quantities of these selected constituents.

Matrix Materials

[0005] The matrix material performs functions such as maintaining thefibers in a set position after the matrix has set or cured, transferringforces between adjacent fibers, providing environmental protection forthe fibers and providing resistance to fluid penetration. Examples ofmatrix materials include polymers such as epoxies, metals, ceramics,refractory materials such as carbon and graphite, and elastomericmaterials such as rubber.

Fibers

[0006] Fibers used in composites include such materials as glass,carbon, metal, jute, and ceramics. The fibers are frequently as small as5 mm in diameter and may be grouped into yarns or filaments of from oneto over 40,000 fibers.

Mandrel

[0007] An object that forms the inside shape of the composite part thatis being fabricated. It may be extracted after the part is fabricated orin some cases, the mandrel may remain inside the composite part. Theshape may be irregular and the mandrel may be either straight or curvedas required for the configuration of the part being fabricated. Theaxial direction of the mandrel is herein taken to be the longitudinalaxis of the mandrel. Fiber or filament orientations are referenced tothe axial direction with the axial direction taken as 0 degrees and thecircumferential direction as 90 degrees.

Pultrusion

[0008] Pultrusion is a process for fabricating long slender compositeparts of constant cross section by pulling the fiber reinforcementsthrough a heated die where the fibers are wet out with uncured resineither prior to the die or while in the die. Heat supplied from the diecauses the resin to cure thus producing a solid composite having thesame shape as the die opening.

Braiding

[0009] Braiding is a process for producing an interlaced textile wherethe interweaving of the yarns is a result of passing the yarns over andunder yarns approaching from the opposite direction. The yarns whichform this braid are generally supplied to two counter rotating feeds.

BACKGROUND—DESCRIPTION OF PRIOR ART

[0010] Fabrication of fiber reinforced plastic composites has become amajor worldwide industry. The modern fibers or reinforcing filaments nowavailable allow components to have physical properties far in excess oftheir metal counterparts. By selection from among a wide variety offilaments such as glass, carbon, arimide, polyethylene, ceramic ormetal, and by careful control of the orientation of these filaments, itis possible to achieve a wide range of physical properties.

[0011] Properties that can be tailored include stiffness, strength,thermal conductivity, thermal expansion, weight, electromagnetic energyabsorption, etc. These various fibers were traditionally imbedded orencased in a plastic matrix but even the matrix technology has beenbroadened to now include matrices such as metal, ceramic, carbon andglass.

[0012] Braiding machines are an alternative to reinforced filaments, butsuch machines have their drawbacks. While braiding machines do notsuffer from the need to secure the filaments by wrapping, they do sufferfrom a limited ability to control fiber distribution. Often a craftsmanmust control many variables such as angles, speed, tension and otherrelated factors in a given task. Braiding machines do not offer theversatility that such a designer desires. Moreover, braiding is limitedby a very slow operating speed compared to the faster and more versatilefilament winding technology.

[0013] The two most efficient methods for fabricating compositecomponents are generally considered to be filament winding andpultrusion. The pultrusion process is more limited in the partconfigurations that can be fabricated and the matricies that can beused. The filament winding process traditionally was based on attachingfilaments to a mandrel and then pulling the band of filaments through abath of resin as the mandrel rotated. Fiber orientation was controlledby translating the bath and fiber band guide along the mandrel as themandrel rotated. By coordination of the translation and rotation, thefiber angle was controlled. This process is very efficient and has beenused to fabricate such items as pipes, pole vault poles and rocket motorcases.

[0014] A disadvantage of existing filament winding machines is that theyhave a limited ability to control the orientation of the filaments. Whenfabricating long shapes, they can not apply filaments in the axialdirection as the filaments would simply fall out of position. This is aserious limitation when fabricating advanced composite materials, suchas carbon fiber reinforced composite tubes, since the axial stiffness ofthe finished tube is seriously degraded by only a few degrees ofdeviation from the axial direction.

[0015] A second problem with existing filament winding machines is thatthey can not change the filament winding angle without spreading thischange over a large axial distance. This limitation is a result of theinability to stop the filaments from sliding in the axial direction.This is a disadvantage in that it limits the ability of the compositesdesigner to specify the desired orientations and requires him to settlefor a machine imposed solution.

[0016] A third disadvantage is that the filaments must very graduallyreverse direction in such a manner as to wrap around the mandrelsufficiently to prevent them from sliding back down the mandrel. Thisresults in a filament buildup at the location where the machine reverseddirection. This buildup is generally either left as excess material oris cut from the final part but is wasted material in either case. Afurther disadvantage that this drawback causes is that it prohibitsshort layers for use with overlaying layers, as the buildup at the endsof the shorter layers will cause a bump in the overlaying plies. Such abump is both unsightly and can also cause structural weakness.

SUMMARY OF THE INVENTION

[0017] The invention relates both to apparatus for, and methods of,forming composite materials based upon a novel over-laying of a primaryset of filaments by a wound second set of filaments which secures theprimary filaments in place in a desired pattern. The method offabricating a fiber reinforced composite structure involves the steps ofusing at least two sets of filaments which are applied to a supportsurface that is chosen to match the desired shape of a finishedcomposite structure.

[0018] In accordance with my invention I choose to place my first fiberset in a non-secured but predetermined orientation on a support surface,such as a mandrel, for example. Let us say that the mandrel is chosen toform a unique sailboat mast having particularly rigorous designcriteria. Moreover, assume that this mast requires many axial filamentstrands, which strands tend to fall away from the mandrel surface assoon as they are being applied.

[0019] In my invention, I over-wrap the first fiber set with at leastone additional fiber set, which additional set extends around themandrel and immediately follows behind and secures the first fiber setto the mandrel in accordance with predetermined orientations.

[0020] In my novel approach such predetermined orientations range fromzero to essentially ninety degrees on said support surface. As anexample, let us assume that the composites designer is presented with aspecification to suit the sailboat mast requirements. Once the mast hasachieved the required layers of filament—perhaps in the order of twentylayers or so—these filament sets are impregnated with a matrix materialwhich solidifies, and when cured, hardens the wound fiber sets into thedesired mast shape. This structure has very precisely controlled fiberorientations for superior strength and reliability. When a supplier istoday faced with liability for any and all catastrophes, such precisefilter alignment is mandatory. Please keep in mind that even a fewdegrees variation from the desired design goal vastly deteriorates thestrength and reliability of the finished part.

[0021] In my embodiment I have also provided a way of removing theimpregnated fiber structure from the mandrel support surface in order toassure that the matrix material and the impregnated fibers have aninside shape that matches the outside shape of my mandrel. In myapparatus for performing my novel method, I have achieved a versatilitywhich allows my mandrel to be either in a stationary position or to moverelative to my source(s) of filament supply. When using spool sets forapplying filaments, I have the added capability to meet designer'srequirements since the spools both rotate and translate relative to themandrel. Indeed, all of the rotating spools may move axially relative tothe mandrel, and may serve to apply axial layers along the longitudinalaxis of the mandrel. These capabilities are important features of thismy invention.

[0022] In my apparatus I have established arrays for the spool setswhich I employ for laying down the fibers. Such spool sets are normallyin a uniform pattern around my mandrel. In conjunction with these spoolsets, I have fixed locations for applying certain filaments as neededfor versatility in meeting the diverse design requirements for compositematerial application of the technology of today. Since the outside shapeof the mandrel fixes the inside shape of the composite material beingformed, I employ, as an option, a collapsing mandrel in order to securean easy and efficient release of the formed composite material.

[0023] This improved filament winding invention, presents a diversenumber of options for securing any given number of yarns to a mandrel asrequired including axial fiber layers. Multiple fiber passes, eachyielding a layer of given orientations from zero to ninety degreesrelative to the longitudinal axis of a mandrel provides valuable freedomin composite material designs. The resulting improvements achieved bythis novel invention substantially eliminate many of the above noteddisadvantages of prior art filament winding or braiding machines, thusallowing the composites designer to produce structurally efficientproducts while fabricating them in an efficient manner.

[0024] Several objects and advantages of the invention are to enablefilament winding of products without resorting to excessive wraps aroundthe mandrel, to allow the use of short plies or layers to be used incombination with longer layers, and to allow selection of a zero toninety degree orientations of the filaments relative to the mandrelaxis. My range thus includes axial layers that run along thelongitudinal axis of the mandrel and also can run transverse to thataxis.

[0025] Still further objects and advantages include the ability to useinexpensive mandrels as will become readily apparent from the followingdetailed description. Additional objects and advantages of the inventionare to apply the filaments without a plastic resin thus allowingsubsequent impregnation by a matrix of the designer's choice.

DRAWINGS

[0026]FIG. 1 is a perspective view of a machine constructed inaccordance with the invention;

[0027]FIG. 2 is a perspective view of a filament application subassemblyor zone for the machine in FIG. 1;

[0028]FIG. 3 includes FIG. 3A and FIG. 3B which are respectively asimplified diagram showing application of primary and secondaryover-laying filaments to a mandrel by techniques of either dry orpre-impregnated filaments.;

[0029]FIG. 4 is an end view of the machine in FIG. 1;

[0030]FIG. 5 is a side view of machine in FIG. 1; and

[0031]FIG. 6 is a top view of the machine in FIG. 1.

DETAILED DESCRIPTION OF THE DRAWING

[0032]FIG. 1 is a perspective view of a machine 100 constructed inaccordance with my invention. A base plate 25 supports the filamentwinding mechanism 50 and translating supports 75 for the mandrel 15. Thewinding mechanism 50 consists of rotating rings 21 through 24 withattached spools 1 through 4 of filaments. The rings 21, etc. can berotated by the motors 5 through 8 which are, in turn, controlled by acomputer which is not shown. Such computer controlled machines are wellknown in this art and need no further description. The mandrel supports14 and 16 are keyed into the base plate 25 with a dove tail thusallowing them to translate as directed by a motor 8 running through apinion 9 and acting on a rack 10 attached to the base plate 25.

[0033]FIG. 2 is perspective view of a typical ring subassembly. Ring 22provides support for four spool brackets 31. Each spool bracket 31 hasone spool, or bobbin, 2 of wound filaments 29 with a friction restraintto provide tensioning for the filaments 29 as they are pulled from thespools 2. The filaments 29 pass through holes 27 in the outer ring 22and then through holes 28 in the innermost filament control ring 30.After passing through rings 22 and 30, the filaments 29 are available towrap onto the mandrel 15 (FIG. 1) which is not shown in this FIG. 2.Filament control ring 30 is supported by four spokes 32 that arethreaded into rings 22 and 30 respectively. Ring 22 has a bearing race33 in each axial face. Ring 22 may be driven by a belt 26 (FIG. 1) thatruns in groove 34 under speed control from a servo motor 8 (not shown inFIG. 2).

[0034]FIG. 3 includes FIGS. 3A and 3B which are respectively asimplified section of winding on a mandrel section and a block diagramof filament winding options and decision controls. FIG. 3A shows severalprimary filament 129 a, 129 b, etc. running axially along thelongitudinal axis 49 of mandrel 15. These primary filaments would tendto fall or scoot around on mandrel 15 when laid down in an axial or zerodegree direction as shown. In accordance with this invention, however,my spool sets such as that of FIG. 2 follow closely behind the primaryfilaments 129 and immediately over-wrap a secondary filament winding 139that secures the primary filaments in place. The inner ring 30 allows mysecondary filaments 139 to be immediately behind the primary filaments129 and thus secures them in place on the mandrel 15 with preciselycontrolled orientations.

[0035]FIG. 3B is a simplified block diagram of my method which showsthat either dry or pre-impregnated fibers may be laid down on a mandrelas desired. Also shown is a matrix filament and a pre-impregnated stepthat allows either type filament to secure the primary filaments inplace on a mandrel. In this flow chart type drawing, bobbins 120 providethe primary filaments which at 122 are applied to mandrel 15 as shown inFIG. 3A. Bobbins 121 provide the secondary filaments 139 which at 123secure the primary filaments 129 by over-wrapping them.

[0036] At decision step 124, a determination is made as to whether ornot the filaments were pre-impregnated. If not, then at step 125, thefilaments are impregnated. Both operational both paths then lead to acuring of the matrix at 126. Step 127 removes the composite structure.

[0037] My mandrel 15 is collapsible to provide for removal of theimpregnated fiber structure from the mandrel support surface whereby thematrix material and the fibers have an inside shape that matches theoutside shape of the mandrel support surface.

[0038]FIG. 4 is an end view of the machine 100 of FIG. 1. This end viewshows the position of mandrel 15 relative to the filament positioningring 30. Note that both the center of the circular surface mandrel 15,and the inner and outer rings 22 and 30 all share a common center.Spools 1 are attached to ring 21 with similar brackets—such as 31 shownin FIG. 2—except that they are shorter as necessary to provide clearanceunder the spools 2 that are attached to adjacent ring 22. Ring 18 is anon-rotating support ring that has a bearing race on the hidden side.Each ring has a bearing race that matches that in the facing ring. Therings thereby support each other with the ball bearings in these racesand with the outer non-rotating support rings 18 being anchored by fixedsupports 26.

[0039] This end view of FIG. 4 also shows how one set of spools may beheld in a fixed position relative to the mandrel. Computer control forthe various spool sets can achieve a rotation from zero on up to higherspeeds as necessary. At zero speed the spool set 1, for example, becomesfixed in place, and in that instance would be laying down four filamentsthat run axially along the mandrel 15. Obviously the number of spoolsand their orientation as shown in these drawings is a matter of choiceand should not be taken as limiting. As a typical example, four spoolsonly are shown, when in actual practice, each such set may involve up toforty spools.

[0040]FIG. 5 shows a side view of the machine. As there shown one seesthat the spools are generally in the same transverse plane as thefilament supply rings such as ring 30 of FIG. 2. Such a location,however, is not to be taken as limiting because such spools may beotherwise located.

[0041]FIG. 6 shows a top view of the winding machine. This view showsthat the spools 1 and 2 are in a common rotating plane but spools set 1is rotating on a smaller diameter than spool set 2. This is best shownperhaps, in FIG. 3. Bar 20 connects mandrel support bases 16 such thatthe bases are held at a set end to end distance. Note that bolts 28anchor plate 20 and can be adjusted to set the spacing of the two bases16 to accommodate different length mandrels 15.

Specific Reference Numerals Matched with Components of the Drawing

[0042]1 spool—or bobbin—of filaments

[0043]2 spool of filaments

[0044]3 spool of filaments

[0045]4 spool of filaments

[0046]5 motor

[0047]6 motor

[0048]7 motor

[0049]8 motor

[0050]9 pinion

[0051]10 rack

[0052]11 belt

[0053]12 belt

[0054]13 belt

[0055]14 mandrel support base

[0056]15 mandrel

[0057]16 mandrel support

[0058]17 mandrel clamp

[0059]18 support ring

[0060]19 motor

[0061]20 bar

[0062]21 ring

[0063]22 ring

[0064]23 ring

[0065]24 ring

[0066]25 base plate

[0067]26 ring support plate

[0068]27 hole

[0069]28 hole

[0070]29 filaments

[0071]30 filament control ring

[0072]31 spool bracket

[0073]32 bracket

[0074]33 bearing race

[0075]34 belt groove

DETAILED DESCRIPTION

[0076] The operation of this invention differs from conventionalcomposite filament winders in several ways. In this invention, themandrel 15 does not rotate because the machine 100 causes the filaments29, FIG. 2, to be wrapped around the non-rotating mandrel 15. I haveachieved operational flexibility by mounting spool sets such as 1, 2, 3etc. on respective outer rings 21, 22, 23, etc. Each outer ring is oneof a pair of concentric rings 30 for each zone, and both rings of thepair are spoke connected such that both rings of a pair rotate around amandrel 15 (FIG. 1) that is positioned relative to the innermost ring30. My spool, or bobbin, sets are in a side by side relationship and arecontrolled independently of each other by a computer in any well knownmanner. Several respective sets of filaments can thus be appliedsequentially and almost simultaneously.

[0077] The outermost spool 2 location, FIG. 2, allows filaments 29 to bebrought through holes 37 in the outer ring 22 and admitted into andthrough openings 28 in the inner filament control ring 30. By passingthe yarns through holes 28 in the inner ring 30, the yarns, orfilaments, 29 can be laid down in close and controlled proximity to thesurface of a mandrel that is positioned within the opening of the innerring 30. Advantageously, the mandrel 15, FIG. 1, is essentially a rollthat fits snugly within the inner ring 30 While shown as concentrictoroids, or rings, the inner and outer geometric configurations, ofcourse need not be circular, but may be varied in shape in accordancewith the particular composite structure being formed. Different shapedmandrels may thus be accommodated within the filament control apparatusof appropriate shape.

[0078] Use of a mandrel-surrounding filament control means such as innerring 22 and the outer ring 30 allows the filament 29 to be positioncontrolled just prior to the filament 29 being wound onto the mandrel15. My apparatus thus achieves a high degree of accuracy in filamentplacement. Moreover, as shown in FIG. 2, spokes 32 fix inner ring 30relative to outer ring 22, and such spokes can be of varying length andinterchangeable so as to allow different shapes for the innermostfilament application set, or zone. By simply changing the inner ringconfiguration—or even leaving it out entirely—different filament shapesmay be laid down on complex shaped mandrels and yet form various typesof composite material structures by closely controlled filamentapplications.

[0079]FIG. 2 illustrates a typical inner and outer ring pair subassemblyin accordance with my invention. The ring 22 supports the spools by useof brackets 31 and outer ring 22 also holds the internal filamentpositioning ring 30. The outer ring 22 is driven by a belt (11, FIG. 1)riding in groove 34 located on the exterior of the ring 22. Ring 22 isheld in position by the ball bearings (not shown) that ride in the races33 on each side of the ring face.

[0080] As a ring pair is rotated and the mandrel is moved axially,several filaments 29, in accordance with the number of spools 2 andopenings 27, 28 of a given bobbin set, will be drawn onto the mandrel inhelical patterns. Angles of the helix can be adjusted from substantiallycircumferential to axial along the longitudinal axis of the mandrel 15by controlling the mandrel translation and the rotation speed of thering pair 22, 30. By using servo motors such as 5, 6 (FIG. 1) to createthese motions, the helix angles can be computer controlled to allow highquality fabrication of complex fiber architectures that might bespecified by an advanced composites designer.

[0081] The winding machine 100 shown in these drawings utilizes foursets of ring subassemblies or zones. Such zones are in side by sideorientation with a common center located on the geometric center of themandrel 15. More or less numbers of rings 22 might be used asappropriate to the objectives of the composites fabricator. In thismachine 100 each of the rings constitutes a zone where filaments can becontrolled independently of the adjacent zones. By loading the spools onthe two inner rings or zones with a high grade structural yarn such ascarbon filaments and the two outer rings or zones with a very low denierglass, the machine will be capable of applying, for example, structuralcarbon in any desired pattern including axial.

[0082] My improved capability is a result of using one of the twoexterior rings (with the light weight glass yarns) to apply asubstantially circumferential helix over the carbon yarns as the carbonis drawn onto the mandrel. This over-wrapping helix or winding securesor fixes the filaments from the inner zones by pressing them against thepreviously deposited yarns and or the mandrel. The use of the twooutermost zones for over-wrapping or fixing the yarns of the inner zonesthus allows my novel machine to function equally well in eitherdirection of translation relative to the mandrel.

[0083] The use of the external rotating rings to secure the yarns inposition allows the structural yarns to be applied without wrapping themaround the mandrel prior to reversing the translation. This permitsshort layers, reduction of waste, fabrication of composite structureswith high axial content and local ply build-up for internalreinforcements in areas of high concentrated force loading. The processis equally effective when used with structural yarns in a helix ratherthan axial orientation in that it allows soft helix angles, as well asquickly changing helix angles, and it eliminates the need to slowlychange the helix angle at the end of the translation.

[0084] Another feature of the machine is the use of rings to helpcontrol the yarn positions just prior to depositing them on the mandrel.These rings can function similar to the wiper rings on a braidingmachine in that the yarns can pass between the rings. Unlike the wiperrings on a braiding machine, the rings can also be made with holes asshown in FIG. 2 such that the yarns pass through the holes for moreprecise positioning of the yarns. This can be done by allowing the ringsto rotate with the mechanism controlling the yarns in each zone.

[0085] Another embodiment of the invention is to hold the mandrel in afixed location and move the winding assembly back and forth over themandrel. This can be a substantial advantage when fabricating longcomposite structures such as sailboat masts as it reduces the amount offloor space that is required.

[0086] While my invention has been described with reference toparticular examples of some preferred embodiments, it is my intention tocover all modifications and equivalents within the scope of thefollowing claims. It is therefore requested that the following claims,which define my invention, be given a liberal interpretationcommensurate with my contribution to the relevant technology.

What is claimed is:
 1. A method of fabricating a fiber reinforcedcomposite structure from at least two sets of filaments from a filamentsupply applied to a non-rotating mandrel support surface chosen to matcha desired shape of said composite structure, said method comprising thesteps of: placing at least one or more first fiber sets in anynon-secured but predetermined orientations of from zero to essentiallyninety degrees on said support surface; and over-wrapping said firstfiber set(s) with at least one additional fiber set, which additionalset extends around the mandrel support surface and secures said firstfiber set in said predetermined orientations.
 2. The method inaccordance with claim 1 and comprising the additional step of:impregnating said fiber sets with a matrix material which solidifiessaid fiber sets into said desired shape; and removing said impregnatedfiber structure from said mandrel support surface whereby said matrixmaterial and said fibers have an inside shape that matches the outsideshape of the support surface.
 3. The method of claim 1 wherein thesupport surface is a mandrel, the filament supply is from bobbins woundwith said filaments and said method comprises the further steps of:applying the fiber from said bobbins to said mandrel by relative motionsbetween said filament supply and said mandrel.
 4. The method of claim 1wherein the support surface is a mandrel having a longitudinal axis andwherein said filaments are delivered from spool sets and comprising thefurther steps of: rotating and/or translating one or more spool setsrelative to said longitudinal axis of said mandrel.
 5. The method ofclaim 4 wherein some of the fibers are drawn from a set of one or morespools having bobbins designed to carry wound fibers, and said methodfurther comprises the step of: arraying said spool set and said bobbinsin a predetermined pattern around said mandrel.
 6. The method inaccordance with claim 5 comprising the additional step of: applying saidfiber filament from a fixed location relative to said support surface.7. The method of claim 6 comprising the further step of: controllingsaid movement of said spool sets such that at least one of said sets isnon rotational while said set still moves axially along saidlongitudinal axis of said non-rotating mandrel.
 8. The method of claim5, wherein said fiber filament sets forming said composite structureemploy the use of one or more sets of spools of fibers from bobbins thatwill be applied to said mandrel, and said method comprises the furtherstep of: removing the mandrel from the composite structure by collapsingsaid mandrel.
 9. The method of claim 1 comprising the further step of:supporting said sets of spools such that the position of said sets arefixed relative to each other in the direction corresponding to the axialdirection of said mandrel.
 10. Filament winding apparatus forfabricating fiber reinforced composite structures from at least two setsof filaments to be applied to a non-rotating support surface chosen tomatch the desired shape of said composite structure, said apparatuscomprising: first means for placing at least one or more first fibersets in any non-secured but predetermined orientations from zero toninety degrees on said support surface; second inner means locatedwithin the first fiber set placing means and having located therein anopening for receiving a filament support surface; and filament controlmeans including said second means for over-wrapping said first fiberset(s) with at least one additional fiber set, which additional setextends around the support surface and secures said first fiber set insaid predetermined orientations on said support surface.
 11. Apparatusfor fabricating fiber reinforced composite structures in accordance withclaim 10 and further comprising: means for impregnating said fiber setswith a matrix material which solidifies said fiber sets into saiddesired shape prior to removal from said support surface.
 12. Theapparatus in accordance with claim 10 wherein said support surface is amandrel and said apparatus further comprises: means for holding saidmandrel in a stationary position; and means for applying the fiber setsto said stationary mandrel by spool sets which are moved relative to thestationary mandrel.
 13. The apparatus of claim 12 wherein the mandrelhas a longitudinal axis and said apparatus further comprises: aplurality of circular spool sets which are in side by side relation witheach other and all sharing a common center aligned with saidlongitudinal axis of said mandrel; and each of said spool sets havingbobbins adapted to receive wound spools of said fiber filaments togetherwith fiber application rings centrally located within said spools andalso having the same common center as said circular spool sets.
 14. Theapparatus of claim 13 wherein the mandrel has a longitudinal axis andsaid apparatus further comprises: means for rotating one or more spoolsaround the mandrel and also moving said spool sets along saidlongitudinal axis relative to said mandrel at a controlled rate suchthat a circumferential helix of said secondary filaments fixes andsecures said primary filaments in place along said mandrel.
 15. Theapparatus of claim 14 wherein some of the fibers are drawn from a set ofone or more spools of fibers and said apparatus further comprises: meansfor arraying said spools in a spaced pattern which surrounds saidmandrel.
 16. The apparatus in accordance with claim 10 and furthercomprising: means for applying said fiber filament from a fixed locationrelative to said support surface.
 17. The apparatus of claim 10 andfurther comprising: means for controlling said movement of said spoolsets such that at least one of said sets is non rotational while stillmoving axially along said longitudinal axis.
 18. The apparatus of claim10 and further comprising: means for removing the mandrel from thecomposite structure by collapsing said mandrel.
 19. Filament windingapparatus for fabricating fiber reinforced composite structures from aplurality of sets of filaments to be applied to a non-rotating mandrelsupport surface chosen to match the desired shape of said compositestructure, said apparatus comprising: first outer circular means havingspools of wound filaments thereon for placing at least one or more firstfiber sets in any non-secured but predetermined orientations from zeroto ninety degrees on said mandrel support surface; second inner meanslocated within the first fiber set placing means and having locatedtherein filament openings for guiding filaments from said outer circularmeans to the inner surface of said second means for secondary filamentplacement and over-wrapping of said primary filaments on the surface ofsaid mandrel support for securing said primary filaments in place onsaid mandrel; and means for controlling the movement of said first andsecond filament supply means such that the primary and secondaryfilaments supply means are rotated around said non-rotating mandrel andboth said first and second means translate together as a fixed unit backand forth along the longitudinal axis of said mandrel while applyingconcentric layers of filaments in said predetermined orientations aroundeach layer on said mandrel support surface.
 20. The filament windingapparatus of claim 12 wherein the mandrel has a longitudinal axis andsaid apparatus further comprises: a plurality of circular spool setswhich are in side by side relation with each other and all sharing acommon center aligned with said longitudinal axis of said mandrel; andeach of said spool sets having bearing races and bearings locatedbetween the inner surfaces of adjacent spool sets which allow adjacentspool sets to be controlled independently of each other during saidfilament layer application.